Many different propulsion systems are used for boats of various kinds for various purposes. Some prior art systems of possible interest with respect to the invention include those disclosed in U.S. Pat. Nos. 2,521,368 (Hingerty Jr.); 3,070,061 (Rightmyer); 3,105,455 (Baldwin); 3,744,446 (Gibbins); 3,793,980 (Sherman); 3,924,557 (Bloch); 3,938,463 (Hecker et al); 3,942,466 (Bunyon); 4,293,304 (Sandstrom); 4,363,630 (Di Vigano); and 4,544,362 (Arneson).
As mentioned above, one aspect of the invention concerns the provision of a propulsion system which enables a "surfacing" operation in a high performance power boat, i.e., a mode of operation wherein the propellor, rather than being fully submerged in the water as is the case with a conventional propellor, is positioned such that the centerline of the shaft is located approximately at the level of the water. Thus, the propellor operates with a portion of the effective disc or blade area thereof in the water and the remainder in the air. A discussion of propulsion systems of this general type is contained in the Sherman patent referred to above which disclosees a marine propulsion system of the "surface propellor" type. In that system the propellor shaft is inclined at an angle and is disposed within a tunnel or channel formed in the hull. The propellor shaft is supported in the tunnel by a combined bearing and stuffing box disposed within the hull and a further bearing supported in the tunnel by a strut located just ahead of the propellor. The Gibbins patent discloses a similar arrangement in a propellor driven planing boat wherein the propellor shaft is mounted within a specially shaped channel in the hull and is mounted between external spaced bearings, located adjacent the hull and astern of the propellor, respectively, so that the propellor shaft extends generally parallel to the surface of the water.
Briefly considering some of the other patents referred above, The Sandstrom patent discloses a flexibly mounted drive arrangement for a ship including a pair of universal joints connecting a propellor shaft to a reduction gear unit, the shaft being supported in a flexibly mounted thrust bearing, and a second set of universal joints serving to connect the gear unit to the engine. The Hingerty Jr. patent discloses a marine thrust bearing assembly, including a pair of oppositely effective bearings, connected to a conventional, inclined propellor shaft. The other patents disclose further propulsion systems of general interest.